Add a RenderBuffer object to store stencil buffers.
Bug #7146141

This change is needed to add a render buffer cache to avoid
creating and destroying stencil buffers on every frame.

This change also allows the renderer to use a 1 bit or 4 bit
stencil buffer whenever possible.

Finally this change fixes a bug introduced by a previous CL
which causes the stencil buffer to not be updated in certain
conditions. The fix relies on a new optional parameter in
drawColorRects() that can be used to avoid performing a
quickReject on rectangles generated by the clip region.

Change-Id: I2f55a8e807009887b276a83cde9f53fd5c01199f
diff --git a/libs/hwui/Extensions.cpp b/libs/hwui/Extensions.cpp
new file mode 100644
index 0000000..edc90fb
--- /dev/null
+++ b/libs/hwui/Extensions.cpp
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Debug.h"
+#include "Extensions.h"
+
+namespace android {
+
+using namespace uirenderer;
+ANDROID_SINGLETON_STATIC_INSTANCE(Extensions);
+
+namespace uirenderer {
+
+///////////////////////////////////////////////////////////////////////////////
+// Defines
+///////////////////////////////////////////////////////////////////////////////
+
+// Debug
+#if DEBUG_EXTENSIONS
+    #define EXT_LOGD(...) ALOGD(__VA_ARGS__)
+#else
+    #define EXT_LOGD(...)
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+// Constructors
+///////////////////////////////////////////////////////////////////////////////
+
+Extensions::Extensions(): Singleton<Extensions>() {
+    const char* buffer = (const char*) glGetString(GL_EXTENSIONS);
+    const char* current = buffer;
+    const char* head = current;
+    EXT_LOGD("Available GL extensions:");
+    do {
+        head = strchr(current, ' ');
+        String8 s(current, head ? head - current : strlen(current));
+        if (s.length()) {
+            mExtensionList.add(s);
+            EXT_LOGD("  %s", s.string());
+        }
+        current = head + 1;
+    } while (head);
+
+    mHasNPot = hasExtension("GL_OES_texture_npot");
+    mHasFramebufferFetch = hasExtension("GL_NV_shader_framebuffer_fetch");
+    mHasDiscardFramebuffer = hasExtension("GL_EXT_discard_framebuffer");
+    mHasDebugMarker = hasExtension("GL_EXT_debug_marker");
+    mHasDebugLabel = hasExtension("GL_EXT_debug_label");
+    mHasTiledRendering = hasExtension("GL_QCOM_tiled_rendering");
+    mHas1BitStencil = hasExtension("GL_OES_stencil1");
+    mHas4BitStencil = hasExtension("GL_OES_stencil4");
+
+    mExtensions = strdup(buffer);
+}
+
+Extensions::~Extensions() {
+   free(mExtensions);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Methods
+///////////////////////////////////////////////////////////////////////////////
+
+bool Extensions::hasExtension(const char* extension) const {
+   const String8 s(extension);
+   return mExtensionList.indexOf(s) >= 0;
+}
+
+void Extensions::dump() const {
+   ALOGD("Supported extensions:\n%s", mExtensions);
+}
+
+}; // namespace uirenderer
+}; // namespace android